TM: Trematodes (iii) - Schistosomes cntd.
early clinical features
cercarial invasion through skin, schistosomular migration via capill venules, then pairing + egg laying
schistosome dermatitis
Swimmer's itch
can happen within 25 mins of invasion
can last 1-2 days
usually in travellers + non-immune people
Tx symptoms
Early acute Katayama fever
due to migration, pairing, egg laying
worm +/or egg antigens cause rapid stimulation of IgG,A,M
circulating immune complexes
glomerularnephritis
serum sickness
2-16 wks after cercarial invasion
usually in non-immune + S japnocium (high egg output)
less likely with S haematobium
acute pyrexial illness with eosinophilia
prolonged prominent fever
malaise, rigors, myalgia, headache, rash, urticaria, lymphadenopathy, loose stool, hepatosplenomegaly
rarely cough, cerebral/spinal symptoms, fatal
late clinical features
established prolonged infection
S Haematobium
usually painless recurrent haematuria
may be microscopic (detectible with dipstick only)
often asymptomatic
dysuria, dribbling, urgency, suprapubic discomfort, recurrent salmonella bacteraemia
affects bladder
hyperaemia mucosa (increased blood flow)
sandy patches in 1/3
grey/yellow fibrosis around intense egg site
calcification
granulomas
vesical ulcers (inflamm)
polyps
SCC - bladder cancer
annual cystoscopy recommended
less commonly affects ureters (but more dangerous)
obstructive uropathy
granulomas
renal failure
usually bilat
fibrotic stenosis
predisposed to gram -ve UTI
seminal vesicles can be enlarged
Frequently found in appendix + rectum
eggs can rarely cause cor pulmonale
Can become ectopic
hepatic fibrosis/granulomas
cut
CNS (with or without symptoms)
pericardium
Intestinal schisto
most asymptomatic
symptoms related to disease load
bloody diarrhoea
abdo pain
S mansoni
pseudopolyposis of colon
mostly in Egypt
multiple pedunculated polyps in colon + rectum
related to intensity of infection
significant blood + protein loss
diarrhoea
tenesmus (continual/recurrent inclination to evacuate the bowels)
focal granulomas along GIT (esp recto-sigmoid)
hepatosplenic schisto
periportal clay pipe hep fibrosis
because it's periportal it's not cirrhosis
egg granulomas block portal tract - portal HTN
splenomegaly (rarely massive)
initially compensatory mechanisms, then liver decompensation in late stage
collat circulation - liver cirrhosis
in lung
embolisation of eggs via portocaval shunts
pul HTN - may lead to cor pulmonale
ICD
glomerulonephritis in kidney
S japonicium
similar to S mansoni
high density of egg laying
less lung/heart involvement, cerebral more common (meningoencephalitis, epilepsy)
neuro-schisto
rare
focal/generalised epilepsy (S japonicium)
paraparesis (partial paralysis of the lower limbs)
myelopathy/transverse myelitis (inflamm of cord) - S mansoni + haematobium
other neuro signs
NB in returning travellers
Dx
stool/urine exam for eggs
sediment/centrifuge urine
conc techniques for stool
FBC
eosinophilia in > 80% of acute cases
anaemia + thrombocytopenia in chronic/advanced
serology
may be diagnostic in patients with no eggs present (e.g. with Katayama syndrome)
expensive
not quantitative or species specific
+ve 3 months before other tests are
rectal/bladder biopsy
to find eggs
if urine/stool -ve but still suspicious
radiology
pul infiltrates on CSR common in acute cases (Katayama syndrome)
abdo US (extent of liver/spleen pathology)
Pelvic US (extent of bladder/ureteric/renal pathology)
coag profile
prolonged PT/INR may be in chronic/advanced cases
U+E raised
LFTs
hyperglobulinaemia + hypoalbuminaemia may be in chronic/advanced cases